It is a bit difficult to find the correct type hose for brake fluid in the right size. You can order it from a few sources but could take just as long to receive the shipment as getting it from MWB. These days shipping is a royal pain in the ass; rates have skyrocketed and services seem to have nearly halted.
Over the years there have been several references to the use of "Tygon" hose for this application. But be aware that "Tygon" is the brand name of the manufacturer. They make a huge variety of hoses in all types of materials, most of which is NOT good for brake fluid. They do offer some that is good for it, so be sure to order the correct type (material) of Tygon brand hose.
en.wikipedia.org
Some X's use the same size supply lines on the brakes and clutch, other use two different sizes. It depends on the nipples installed into the master cylinders - which are available in both sizes and will fit in both masters. So if you have enough of the "brake" hose then maybe you can replace the nipple on the clutch master and use that hose. But you also need to check what size nipple is on the reservoir - again it can be either size.